Effects of Heat Treatment Temperatures on Microstructure, Mechanical Properties and Tribological Properties of Crtisin Coatings

Abstract

The effect of high-temperature heat treatment on the microstructure, mechanical properties, and tribological properties of CrTiSiN coatings were investigated in this study. It has been found that the heat treatment temperature significantly affected the microstructure of the coatings. As the heat treatment temperature increases from 850 ℃ to 1000 ℃, the O content of the coating surface layer gradually increases while the N content decreases significantly. A significant number of nitrides in the coating surface layer have been converted into oxides. The CrTiSiN coating has NaCl-type crystal structure mainly consisting of a solid solution phase formed by TiN and CrN. The CrTiSiN coating shows four crystal surfaces (111), (200), (220), and (311), and columnar crystals.The oxide layer exhibited a stratified structure. While TiO2 was on the top layer, and the combination of Cr2O3 and SiO2 layers were located below the TiO2 layer. A decrease of hardness were observed. However, a slight increase in coating hardness occurs at 1000°C due to the change in the composition of the generated oxides. Meanwhile, the internal stress of the coating increases. The friction coefficient remains relatively stable. However, an increase in wear rate were detected, while the lowest wear rate of 2.205×10-7 mm3 /(N·m) was detected at 850 ℃.The wear mechanism of the coating against ZrO2 ball was oxidative and adhesive wear. Therefore, within the selected experimental temperature range, the CrTiSiN coating treated at the preferred heat temperature exhibits the most favorable mechanical and tribological properties.

Keywords: CrTiSiN; microstructure; mechanical properties; tribological properties; heat treatment